<!DOCTYPE html>
<title>Tests mouse autoscroll when scrollbar is dynamically deleted.</title>
<script src="../../../resources/testharness.js"></script>
<script src="../../../resources/testharnessreport.js"></script>
<script src="../../../resources/gesture-util.js"></script>
<script src="../../../resources/scrollbar-util.js"></script>
<div id="content" style="height: 10000px; width: 10000px; border: 1px solid;"></div>
<script>

  function resetScroller() {
    window.scrollTo(0, 0);
    document.getElementById("content").style.width = "10000px";
    document.getElementById("content").style.height = "10000px";
    document.documentElement.style.overflowX = "visible";
    document.documentElement.style.overflowY = "visible";
  }

  function shortenHorizontalScroller() {
    document.getElementById("content").style.width = "10px";
  }


  function shortenVerticalScroller() {
    document.getElementById("content").style.height = "10px";
  }

  function createScrollPromise(callback) {
    return new Promise((resolve, reject) => {
      waitForScrollEvent(window).then(() => {
        callback();
        resolve();
      });
    });
  }

  // When pointerdown occurs, an autoscroll task gets scheduled to be
  // executed after 250ms. This code checks that the renderer doesn't
  // crash when the scrollbar is dynamically deleted while an auto
  // scroll task is scheduled.
  promise_test (async () => {
    await waitForCompositorCommit();
    resetScroller();
    assert_equals(document.documentElement.style.overflowY, "visible",
    "Scroller is expected to be scrollable in the Y direction");

    const scrollPromise = createScrollPromise(shortenVerticalScroller);
    await mousePressOn(downArrow().x, downArrow().y, 300);
    await scrollPromise;

    assert_equals(document.getElementById("content").style.height, "10px",
    "Scroller height should have been reduced to 10px.");
  },"Test same-axis autoscroll when vertical scrollbar deleted.");

  promise_test (async () => {
    await waitForCompositorCommit();
    resetScroller();
    assert_equals(document.documentElement.style.overflowY, "visible",
    "Scroller is expected to be scrollable in the Y direction");

    const scrollPromise = createScrollPromise(shortenHorizontalScroller);
    await mousePressOn(downArrow().x, downArrow().y, 300);
    await scrollPromise;

    assert_equals(document.getElementById("content").style.width, "10px",
    "Scroller width should have been reduced to 10px.");
  },"Test cross-axis autoscroll when vertical scrollbar deleted.");
</script>
